Taraxacum officinale

Taraxacum officinale

Taraxacum officinale, commonly called Dandelion, is a herbaceous perennial plant of the family Asteraceae (Compositae). It can be found growing in temperate regions of the world were it is found in lawns, roadsides, and on disturbed banks and shores of water ways and other areas with moist soils. T. officinale is considered a weedy species, especially in lawns and along roadsides, it is sometimes used as a medical herb and in food preparation. As a nearly cosmopolitan weed, Dandelion is best know for its yellow flower heads that turn into round balls of silver tufted fruits that blow away on the wind.

Description

Taraxacum officinale grows from generally unbranched taproots and produces one to more than ten stems that are typically 5 to 40 cm tall but sometimes up to 70cm tall. The stems can be tinted purplish, they are upright or lax, and produce flower heads that are held as tall or taller than the foliage. The foliage is upright growing or horizontally orientated, with leaves having ether narrowly winged petioles or they are unwinged. The stems can be glabrous or are sparsely covered with short hairs. The 5–45cm long and 1–10 cm wide leaves are oblanceolate, oblong, or obovate in shape with the bases gradually narrowing to the petiole. The leaf margins are typically shallowly lobed to deeply lobed and often lacerate or toothed with sharp or dull teeth. The calyculi (the cup like bracts that hold the florets) is composed of 12 to 18 segments: each segment is reflexed and sometimes glaucous. The lanceolate shaped bractlets are in 2 series with the apices acuminate in shape. The 14 to 25mm wide involucres are green to dark green or brownish green with the tips dark gray or purplish. The florets number 40 to over 100 per head, having corollas that are yellow or orange-yellow in color. The fruits, which are called cypselae, range in color from olive-green or olive-brown to straw-colored to grayish, they are oblanceoloid in shape and 2 to 3 mm long with slender beaks. The fruits have 4 to 12 ribs that have sharp edges. The silky pappi, which form the parachutes, are white to silver-white in color and around 6 mm wide. Plants typicaly have 24 or 40 pairs of chromosomes but some plants have 16 or 32 chromosomes. Plants have milky sap and the leaves are all basal, each flowering stem lacks bracts and has one single flower head. The yellow flower heads lack receptacle bracts and all the flowers, which are called florets, are ligulate and bisexual. The fruits are mostly produced by apomixis.

Taxonomy

The taxonomy of the genus Taraxacum is complicated by the means of propagation employed by the species, and the taxonomy and nomenclatural situation of Taraxacum officinale is not yet fully resolved. The introduced plants to north America are obligate gametophytic apomicts and triploids. There are three subspecies of Taraxacum officinale including:

Taraxacum officinale ssp. ceratophorum (Ledeb.) Schinz ex Thellung which is commonly called Common dandelion, fleshy dandelion, horned dandelion or rough dandelion. It is native from Canada and western USA.

Taraxacum officinale has had a number of different English common names including: blowball, lion's-tooth, cankerwort, milk-witch, yellow-gowan, Irish daisy, monks-head, priest's-crown and puff-ball; other common names include, faceclock, pee-a-bed, wet-a-bed, canker-wort.

Carl Linnaeus named the species Leontodon Taraxacum in 1753. The genus name Taraxacum, maybe derived from the Arabic word "Tharakhchakon", or it could be from the Greek word "Tarraxos". The common name Dandelion comes from the French phrase "dent de lion" which means "lion's tooth", a reference to the jagged shaped foliage.

Weeds

Taraxacum officinale is a common colonizer after fires, both from wind blown seeds and seed germination from the seed bank. The seeds remain viable in the seed bank for many years, with one study showing germination after nine years. This species is a somewhat prolific seed producer, with 54 to 172 seeds produced per head, and a single plant can produce more than 5,000 seeds a year. It is estimated that more than 97 000 000 seeds/hectare could be produced yearly by a dense stand of dandelions. When released, the seeds can be spread by the wind up to several hundred meters from their source, the seeds are also a common contaminate in crop and forage seeds. The plants are adaptable to most soils and the seeds are not dependent on cold temperatures before they will germinate but they need to be within the top 2.5 centimeters of soil.

Distribution

Common Dandelion has its origin in Eurasian and has become naturalized throughout North America, It occurs in all 50 states of the USA and most Canadian provinces, it has been introduced into southern Africa, South America, New
Zealand, Australia, and India.

Uses

Taraxacum officinale is used to make dandelion wine, the greens are used in salads, the roots have been used to make a coffee like drink and the plant was used by Native Americans as a food and medicine.

While the dandelion is considered a weed by most gardeners and lawn owners, the plant does have several culinary uses, and the specific name officinalis refers to its value as a medicinal herb. Dandelions are grown commercially on a small scale as a leaf vegetable. The leaves (called dandelion greens) can be eaten cooked or raw in various forms, such as in soup or salad. They are probably closest in character to mustard greens. Usually the young leaves and unopened buds are eaten raw in salads, while older leaves are cooked. Raw leaves have a slightly bitter taste. Dandelion salad is often accompanied with hard boiled eggs. The leaves are high in vitamin A, vitamin C and iron, carrying more iron and calcium than spinach.

Dandelion flowers can be used to make dandelion wine, for which there are many recipes. It has also been used in a saisonale called Pissenlit (literally "wet the bed" in French) made by Brasserie Fantôme in Belgium. Another recipe using the plant is dandelion flower jam. Ground roasted dandelion root can be used as a coffee substitute.
Dandelion root is a registered drug in Canada, sold principally as a diuretic. A leaf decoction can be drunk to "purify the blood", for the treatment of anemia, jaundice, and also for nervousness. Drunk before meals, dandelion root coffee is claimed to stimulate digestive functions and function as a liver tonic. "Dandelion and Burdock" is a soft drink that has long been popular in the United Kingdom with authentic recipes sold by health food shops. It is unclear whether cheaper supermarket versions actually contain extracts of either plant.

The milky latex has been used as a mosquito repellent;the milk has also been used to treat warts, as a folk remedy.

Yellow or green dye colours can be obtained from the flowers but little colour can be obtained from the roots of the plant.